The invention generally relates to laboratory instruments and processes for collecting samples and, more particularly, to laboratory instruments and processes to generate fluid samples that have known concentrations of a targeted particulate material.
In chemistry and the biological sciences, laboratory instruments and techniques exist for separating a composite material, such as a soil sample or a blood sample, into its component materials. Typically, the isolation step is performed as a preliminary step to further testing that centers around the characteristics of the isolated component.
It is often a difficult and cumbersome task to isolate one element of a composite material. One typical approach is to employ a centrifuge to separate composite materials into the individual elements. In practice, a lab technician can place the composite material into a test-tube-like container. The lab technician inserts the container into the centrifuge and activates the centrifuge for sufficient time to separate out the element or elements of interest. Upon completion of a centrifugal separation, the lab technician removes the container and extracts from the stratified sample the element or elements.
Although centrifugal separation can work well, it is typically labor-intensive and often poorly suited for isolating small particulate matter, such as cellular material. Moreover, the centrifugal technique fails to provide a separation process that readily yields samples with known concentrations of a targeted element.
Accordingly, it is an object of the invention to provide laboratory instrumentation and processes that generate samples with known concentrations of a selected particulate material.
It is a further object of the invention to provide laboratory instruments and processes that detect samples having low concentrations of a targeted material.
It is yet a further object of the invention to provide laboratory instrumentation and processes that provide measures of the integrity of a performed diagnostic analysis.
It is still a further object of the invention to provide instrumentation and techniques that provide information representative of the severity of a disease.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
Instruments and processes according to the invention provide for the preparation of a fluid sample that has a substantially known concentration of a select particulate matter. In one aspect, the invention is understood as laboratory instruments for sample preparation. These instruments can include a filter that is submersible within a fluid suspension of particulate matter. To collect particulate matter from the fluid suspension, the instruments can cause a fluid flow that pulls fluid across the filter to trap particulate matter against one surface of the filter. The instruments can then remove the filter from the fluid suspension and dispose the filter above a collection vessel such that the side of the filter that is carrying particulate matter is positioned above the opening of the collection vessel. The laboratory instruments can then send a collection fluid through the filter in a direction opposite to the original fluid flow, thereby washing the particulate matter off the filter and into the collection vessel. The laboratory instruments according to the invention can provide samples having a known concentration by passing a known volume of collection fluid through the filter, thereby trapping the collected particulate matter within a known volume of collection fluid.
In one aspect, the invention is understood as methods for reproducibly generating a fluid sample having a select concentration of particles. Methods of the invention can include the steps of providing a fluid suspension of dispersed particles, disposing a filter having a first side and a second side within the fluid suspension and flowing the fluid suspension across the filter from the first side to the second side, such that a substantially known quantity of particles collect onto the first side of the filter, removing the filter and the particles collected thereon from the fluid suspension, and passing a known volume of collection fluid through the filter to remove substantially the particles collected on the first side, and to collect the particles within the known volume of collection fluid.
In one practice, the processes according to the invention can include a step of disposing a filter that includes providing a particle collection device having an intake port and an evacuation port, and having the filter spanning the intake port. Further practices according to the invention can include a step of generating a fluid flow by evacuating the particle collection device to draw fluid across the filter and through the intake port and into the collection device.
In a further practice of the invention, these processes can include a step of passing a known quantity of collection fluid through the filter by applying a select fluid pressure within the collection device to force fluid collected therein back across the filter. Further, when passing a known volume of collection fluid through the filter, the processes of the invention can include the step of disposing the filter collection device at a select angle to generate thereby a drip of collection fluid that has the particles collected therein.
In a further practice, the invention can include the steps of selecting a filter that has a pore size adapted, dimensionally, for collecting particles of a pre-determined size. These filters can include cellulose, polyester, polycarbonate, nylon and teflon filters, and can have pore sizes suited for collecting a target material. For cells, filter pore sizes typically range between 0.2 and 20 microns.
The processes according to the invention can also include further steps for analyzing the particles and fluid samples that are collected. For example, the processes of the invention can include the further steps of lysing the collected particles, or providing a portion of the collected particles in the known volume of collection fluid as a sample for diagnostic assay.
In a further practice, the processes according to the invention can include the steps of causing a flow of fluid and measuring a characteristic representative of the quantity of particles collected against the filter. Moreover, the processes can interrupt the step of flowing the fluid suspension in response to a measured characteristic that represents a preselected quantity of particles. Accordingly, processes according to the invention can monitor characteristics of the fluid flow to determine when a preselected quantity of particles have collected against the filter.
In a further aspect, processes according to the invention can direct the fluid suspension across the filter by applying a known pressure to the fluid suspension. Further these processes can apply pressure to the fluid suspension as a succession of know pressures. In this practice, the processes can measure a characteristic representative of the rate of change of pressure and can determine from this measured characteristic a quantity of particles collected against the filter surface.
In a further aspect, the invention provides processes that can be employed for incrementally achieving a desired concentration of particles within a known volume of fluid. For example, the processes of the invention can be iterative in that upon collecting a first sample of collected particles within a known volume of fluid, this fluid sample can be again processed according to the invention to provide a fluid sample having an alternative concentration of particles.
In a further aspect, the invention provides apparatus for reproducibly collecting a sample having a select concentration. Such apparatus can comprise a filter having a first side and a second side and being submersible within a fluid that contains a quantity of particles, an element for flowing the fluid across the filter in a direction that travels from the first side to the second side such that a substantially known quantity of particles collects onto the first side of the filter, an element for removing the filter and the particles collected thereon from the fluid suspension, and an element for passing a known volume of collection fluid through the filter to remove substantially the particles collected on the first side and to collect the particles within a known volume of collection fluid.
As described above, the invention offers significant advantages over known methods for collecting fluid samples by providing systems and methods that generate fluid samples of particulate material in select concentrations. Moreover, the invention further provides automated laboratory instrumentation that can perform each step of the fluid sample preparation process such that the systems automatically and reproducibly provide fluid samples each having select and known concentrations.
These and other advantages of the invention will be more fully understood by reference to the following detailed description in conjunction with the accompanying drawings in which like reference numbers refer to like elements.